There has been tightened regulations on tourist visa extensions here in Thailand. They mostly apply to back-to-back visa runs – especially by land border crossings. Also specific countries are being targeted more due to the amount of people from those countries here living and working without work permits. Namely Philippines, Russia, South Korea & Vietnam.
The best solution is to have a proper tourist visa that can be extended an additional 30 days at the immigration office. People should no longer rely on doing land visa runs on a regular basis (to Cambodia, Laos, Myanmar or Malaysia). Thai immigration officials at these borders have individual discretion to only grant 7-day stamps instead of the normal 15-day & 30-day stamps normally given.
There are various companies around Thailand that provide a variety of visas for different situations. Tourist & Non-Immigrant visas for retirement, marriage, study, business and dependents are all available. One of the most respected visa service companies in Bangkok is called Bangkok Buddy. They are located on Sukhumvit Road next to the Asok BTS. I recommend them highly.